暴时行星际穿透电场与电离层效应的卫星观测

Penetration of IEF into low-latitude and its ionospheric effects as seen by multi-satellites during storm time

联合利用Geotail卫星、ROCSAT-1卫星和DMSP卫星等观测数据,分析了2000年7月15-16日超强磁暴期间行星际穿透电场的特征及低纬电离层响应。研究得到以下主要结果:1)磁暴主相期间,位于近地太阳风中的Geotail卫星观测到行星际电场晨昏分量迅速增强达60 mV/m,与此同时,ROCSAT-1卫星在低纬电离层中几乎即时地观测到垂直于磁场的离子向上漂移速度达300 m/s以上,表征行星际电场穿透至低纬电离层。分析表明:在正午和黄昏扇区穿透电场为东向,引起低纬电离层离子向上漂移,穿透效率约为13-19%;而在午夜前扇区,穿透电场极性相反,使离子向下漂移,穿透效率高达30%;行星际电场穿透持续时间达3小时以上。2)磁暴期间,低纬电离层发生剧烈变化。GPS/TEC观测显示美洲扇区黄昏附近的中纬度电离层发生SED现象、同时DMSP卫星观测到纬度范围大大扩展的电子密度深度耗空的赤道区等离子体槽、ROCSAT-1卫星观测到暴时离子密度变化呈现较复杂的图像。

With multi-satellite observations during the super magnetic storm period of 15-16 July,2000,the electric penetration and its ionospheric effects are analyzed.It is shown that the dawn-dusk component of interplanetary electric field（IEF）observed by Geotail was largely increased to 60mv/m during the storm main phase.concurrently large upward ion drifts as high as 300 m/s was observed in the low-latitude,indicating that the IEF penetrate into low-latitude.It manifests large upward ion drift（eastward E-field） at noon/sunset sectors with penetration efficiencies of about 13-19%,while it does downward ion drift（westward E-field） with a penetration efficiency as high as 30% at pre-midnight sector.In response to the storm,especially to the penetration of IEF,the low-latitude ionosphere changed dramatically as seen by GPS/TEC records and DMSP measurements in-situ.A so-called storm-enharnced density（SED） event manifested in TEC map was seen around the sunset American sector,along with very deep depletion in a widened equatorial plasma trough seen in DMSP data and complicated pattern of storm-time changes in ion density by ROCSAT-1.